1. Field of the Invention
This invention relates to cameras, and particularly cameras with an operation switch for performing an information setting or function controlling operation.
2. Description of the Prior Art
In many conventional cameras, photographic information is set with a dial provided with a built-in sliding resistor or a substrate having a four or five bit patternized code. Setting a film sensitivity value, for example, involves adjusting the position of the dial, which is intermittently marked with ASA/ISO value figures 100, 125, 200, 250, 400, etc., to a specific value. Such conventional setting devices require a complex arrangement of the component parts of the dial. Additionally, operation of the dial is quite difficult when an information display system is arranged within a view finder, because the dial must be operated while watching the display within the view finder.
To solve this problem, a proposal has been made for a setting device with an up button and a down button arranged such that either the up button or the down button is continuously depressed depending on whether the presently displayed setting value should be increased or decreased. The up or down buttons are released when a desired setting value is displayed. This provides a simple setting device. However, since the setting value display system is still arranged with the view finder, together with other photographic information, the display cannot be easily discerned. Besides, the operability of the device is still poor because the up or down button must be operated while watching the inside of the view finder.
Cameras have been contrived with a display device such as a liquid crystal or light emitting diode display device disposed on the outside of the camera, as shown in FIGS. 1(a) and 1(b) of the accompanying drawings. In the camera represented by FIG. 1(a), an up-shifting button 1a and a down-shifting button 1b are vertically aligned along one side of a camera part 2 having a pentagonal prism disposed therein. A display device 3, a shutter release button 4 and a photographing mode selection dial 5 are arranged on one side of the up- and down-shifting buttons 1a and 1b. In the camera represented by FIG. 1(b), the up button 1a and the down button 1b are laterally aligned behind the shutter release button 4. The display device 3 is disposed on the side of the pentagonal prism part 2.
The operability of the cameras shown in FIGS. 1(a) and 1(b) has not been satisfactory. The camera shown in FIG. 1(a) requires the camera operator to shift his or her manner of holding the camera for taking a photograph to a different manner of holding for a photographic information setting operation. Furthermore, the operating finger tends to obstruct the view of the display device 3 and the photographing mode selection dial 5 tends to hinder the setting operation. In the camera shown in FIG. 1(b), the button 1a and 1b must be operated by bending an index finger, because they are located behind the shutter release button 4. This location is also disadvantageous in terms of operating the camera.
Another problem with the prior art arrangements shown in FIGS. 1(a) and 1(b) is that the up- or down-shifting buttons 1a or 1b are apt to be inadvertently operated while the camera is being carried by the photographer. Further, since the two setting shift buttons 1a and 1b are arranged within a small limited space on the upper surface of the camera, they are inevitably small and located near each other. Therefore, it is highly probable that the photographer will mistake one of them for the other or inadvertently operate both. In that event, the setting value of photographic information is shifted downward and upward contrary to the intention of the photographer. The possibility of such mis-operation is especially salient where the up-shifting and down-shifting buttons 1a and 1b are laterally arranged, as shown in FIG. 1(1). In other words, when the photographer attempts to operate the button 1a, which is located farther from the operating finger of the photographer, it is quite likely that the other button 1b located closer to the finger will be erroneously operated together with the farther button 1a (located on the side of the optical axis of the photo-taking lens of the camera).
Further, according to the prior art shown in FIG. 1(a) and 1(b), the up-shifting or down-shifting buttons 1a and 1b are pushed down while a light measurement start switch is turned on. However, in a conventional camera, the first half-stroke in the depression of the shutter release button 4 is what turns on the light measurement start switch. The shutter is released by the second half-stroke of the shutter-button depression. With either of the prior art arrangements applied to the conventional camera, two fingers of one hand gripping the camera must be used for operating two buttons. While the shutter release button 4 is pushed down through the first half-stroke with, for example, an index finger, the up-shifting or down-shifting button 1a or 1b must be pushed with another finger of the same hand. Then during that operation, which is performed with the same hand, the shutter release button 4 is apt to be erroneously pushed down for the second half-stroke. These prior art constructions thus present a problem in terms of simplicity of operation.